Annular debarking mechanism and control



Feb. 16, 1960 B. E. FITZWATER 2,925,107

ANNULAF. DEBARKING MECHANISM AND CQNTROL Filed May 6, 1958 5Sheets-Sheet l l IN V EN TOR.

Br-uceE. Ffi'zwa her Feb. 16, 1960 B. E. FITZWATER 2,925,107

ANNULAR DEBARKING MECHANISM AND CONTROL Filed May 6, 1958 3 Sheets-SheetI2 nvmvrox Bruce E. Fl'i'zwaker Feb. 16, 1960 B. E. FITZWATER ANNULARDEBARKING MECHANISM AND CONTROL 3 Sheets-Sheet 3 Filed May 6, 1958INVENTOR. Br'uceE. F1 1% wafer llllll I:

Uflied Sa e t 2,525,107 ANNULAR DEBARKING MECHANISM AND CONTROL Applicaon M y 1958, serial N9 733370 firearms, ((1144-2023) a i .This inventionrelates to, log vdebarking apparatus, and more particularlyto ring-typewdebarking apparatus employing annular debarking. mechanismrevolving about thepcriphery of a log threaded through the middlethereof, and operable to peel or skin the bark from the log as itprogresses therethrough. j j j i 1 A general object of the invention isto provide debarkapparatus of the type described which includes novelmechanism expediting setting up of the apparatus so that'the annulardebarking mechanism is truly centered with; respect to a log beingtreated. I he mechanism cor: relates the positionof theannular debarkingmechanism; with the position of a clamping mechanism feeding a log,; sothat the latter mechanism may be used as an indexing means for thedebarking mechanism. Another object is to provide apparatus of the abovedescription which includes mechanism operable automatically toreposition the ring debarking mechanism as a logtravelsdherethrough whennecessary to take care of the taper of a log, and other irregularitiesin shape.

A further object is to provide hydraulic, balancing means for the ringdebarker whereby the weight of the debarker is substantially entirelysupported during operation: of; thejdebarking apparatus. This latterfeature contributesto rapidity in response when adjustments are made intheposition of the ring debarker.

' conventionally ring-type log debarkers comprise an annular debarkerframe mounting a number of radially Patented Feb. 16, 1960 feed clampmechanisms and the debarking ring whereby movement of one is accompaniedby movement of the other, and the total distance traveled by one hears afixed ratio to the total distance traveled by the other. A cross-sectionof a log normallyhas a substantially circular outline. From this itfollows that the distance between the two sides of a log, and thedistance between a side and the middle of a log have the ratio of about2 to 1. Thus positioning of the ring debarker so that its radial centercoincides with the center of a log has-a definite relationship withrespect to the adjustment necessary in the opposed clamp mechanisms tobring them tightly against the sides of a log. By interconnecting theclamp mechanisms and debarker ring, accurate, indexing of the debarkerring is possible merely by posi; tioning the infeed clamp mechanismstightly against the oppositeoutersidesofalog :q, Thedebarking apparatusalso includes hydraulic means for producing a constant butyieldable'clampingpressnre in ,the. opposed clamp mechanisms, so thattheclamp ing mechanisms can move in and out as they follow a log contourdown the length of a log. An obvious example in variation of log contouris illustrated by the taper of the normal log. For instance, arelatively. long l og may-have a diameter at one end of roughly twofeet, and;

a diameter atits other end of maybe a foot.- As the log advances betweenthe clamping mechanisms, they move together to take careof this changingdiameter of the log, By coordinating movement of the ring debarker withthe clamp mechanisms, the ring debarker also shifts so thatits radialcenter will tend to stay aligned with the log center.

A more specific object of the invention is to provide for debarkingapparatus having an annular deharkena servo motor connected to andpositioning the annular; debarker, andcontrols for the servo motoractuated by movement of the opposed clamp mechanisms feeding a;

inwardly projecting debarking arms or members. These debarking arms,onrotation'of the annular frame relative to a log passed therethrough,are operable to scrape or otherwise vcut away the bark and cambium layerfrom a log. The arms ordinarily are pivotally mounted so that the innerends of the arms move inwardly against the surface of a log.Thedebarking apparatus also normally includes clamping means to one sideof the annular debarker frame for gripping onto a log and funneling itinto the center of the debarker frame.

One of the majordifficulties confronting the user of suchequipment isthe proper. positioning of the annular debarker frame with respect tothe clamping means feeding a log. Optimum results are obtained when thecenter of a log fed to the annular debarker'f rame'coincides with. theradial center of the frame. When the center of a log is olfset from thistruly centered position, excessive fraying and-scraping of the ends andsides of a log occurs with consequent loss of weed material.

In prior constructions employing power-actuated means for positioningthe annular debarking mechanism, positioning has been'for the most parta matter of approximation. An operator has first had to judge thediameter of a log, and then. make an educated guess as, to the properposition for the annular debarking mechanism. Such adjustments are notaccurate, and further, no provision is made to take care ofirregularities in the contour of a log, such as the taper normallypresent in a log.

This invention contemplates debarking apparatus hav new ia swsss ti s e:t v its s r s log to the ring debarker. The servo motor is initiallyactuated when relative movement .of the clamp mechanisms is firstproduced, either toward or away from each other. The servo motor onactuation moves the annular debarker in a direction related to thedirection of movement in the clamp mechanisms but at a reduced rate ofspeed. The control for the servo motor includes a novel feedba'cksystem', which functions to indicate when the debarker ring has arrivedat a proper position related toa new' adjusted position of the clampingmechanisms.

The control means for the servo motor comprises a pair ofpiston-cylinder devices each of which have equaldisplacements onopposite sides of the piston for the device. That is, for a given amountof movement of a piston in a device, the change of the size of thechamber on one side of the piston equals exactly the change of the sizeof the chamber on the other side of the piston. One of thepiston-cylinder devices has a total volume displacement equal to twicethat of the other. Connections are I made so that movement of thedebarker ring produces system is easily installed on debarkingequipment, "is free of extensive mechanical linkages, and accurate inopera-" a corresponding relative movement of the piston of oneof'thepiston-cylinder devices. This piston pumps fluid to the other ofthe piston-cylinder devices, thereby to produce relative movementbetween the piston and cylinder of'the other device, but at a differentalthough related speed. A follower attached to this otherpiston-cylinder travels in a path adjacent to another part movable witha clamp member. The relative position between this other part andfollower control the servo motor. The

tion.

These and by, theninvention, which is described hereinbelow in coni a sse w he sweet n s t isss. whsts na a other objects and advantages areattained forwardly toward the ring debarkcr.

Fig. 1 is a side elevation of debarking apparatus according to thisinvention showing the apparatus with a log passing down the lengththereof;

1 Fig 2 is a section view along the line 2-2 in Fig. 1, illustrating thering debarking mechanism present;

Fig. 3 is a schematic showing of an hydraulic control system suchas maybe used to coordinate movement of the ring deba'rker and infeed' clampmembers oi the apparatus; and

Fig. 4 illustrates a modification of the control system that may be usedfor positioning the ring debarker Referring now to the drawings for adescription of a specific embodiment of the invention, and in particularto'Figs. I and 2, 10 indicates generally the debarking apparatus; Theapparatus includes a frame 11 having longitudinal members 12, verticalmembers 13, and transverse members 14, properly; secured together toform asl'r'eletoriized, generally rectangular structure with a passagethrough the iniddle thereof to accommodate-alog passed eudwise throughthe apparatus. 1

"' Me'untedjon the frame at the infeed'or' rear end there- 7 of-(atiheleftof the figure in Fig. 1') is an infeed clampingman's generallyindicated at 16; In front of clamping ineans'lfi is an annular debarkingmechanism or ring'deba'rker 17, and mounted on the frame in front ofmechanism 17 at th'e'outfe'ed end of the apparatus is an Outfeedclamping means indicated at 18. In operation, logs ar e introduced intoclamping means 16 where theyare'held securely and at the same timetransported Here their bark is removed, and the tail ends of the logspulled from the debarker by clamping means 18. conventionally aconveyor, such as conveyor-19, feeds logs endwise to clamping means 16.

Infeed clamping means 16 comprises three yo-yo rolls 21-; 22 and 23.These all have substantially the same shape, each having built-up endperipheries and reduced center pe'ripheriesintermediate their ends, asindicated by thedot-ted, outlines of the infeed rolls superposed overthe section view of Fig. 2., Conventiohally the peripheral surfaces ofthe rolls are provided with flutes or other gripping means to increasethe bite of the rolls.

Lower rolls 21, 22 constitute a lower clamping mechanism of the infe edclamping'means, and upper roll 23 iunctions as an upper clampingmechanism'spaced from and" opposed to the lower clamping mechanism. Thelower rolls rotate about fixed axes, and are rotatably mounted on frame11 by bearing members 27, 28 tatably receiving journal portions of shaftextensions provided each roll. The lower rolls are interconnected torotate together by means of a chain 29 reeved about sprockets secured toa shaft extension of each roll. A driving chain 31 and motor 30 rotatethe lower rolls in unison and in a clockwise direction viewing the rollsin Fig. 1.

Upper roll 23 of the upper clamping mechanism of the infeed clampingmeans is provided with shaft extensions which are rotatably mounted inbearings 36 These bearings are carried on a pair of opposed slidingblocks 37, one supporting each end of the roll (one of which is obscuredin Fig. 1). These blocks each have formed along their end edgeselongated grooves which slidably seat on oppositely disposed flanges 38projecting inwardly into the space between vertical members. 13 at theinfeed end of the apparatus. The flanges provide rail means guiding ablock in vertical movement toward and away the lowerclamping mechanism.

,Power actuated means move upper roll 23 toward and aw-ay'the lowerclamping mechanism. In the embodiment: illustrated, this. takes thefornrof an expansiblecontractible, double action piston-cylinder orjack"4l-" mounted with the cylinder portion thereof secured to atransverse member 14- of the frame and with the rod of the j'ackextending downwardly andaflixed' to a brace bar 42 interconnectingblocks 37 on either sidevof the apparatus. r

Outfeed clamping means 18 is similar to infecd clamping means 16.Outfeed clamping means 18 has an upper roll 46 which is mounted forvertical movement toward and away a lower set of rolls -47, 48. Theupper roll constitutes an' upper clamping mechanism and-the lower pairof rolls function as a lower clamping" mechanism. As in the case in theinfeed clamping means, the upper of the rolls 46 is mountedfor verticalmovement toward and away the lower clamping mechanism by blocks- '51carrying bearings supporting journal portions of'shaft extensions forthe roll. Blocks 51 are slidable vertically in flanges or ra ls 53, 54projecting toward each other from rear uprighvmembers-B; Double actingjack or piston-cylinder 52 powers the upper clamping mechanism up anddown. V

' The ring debarkermechanism disposed intermediate the in'feed andoutfeed'elam ing mea s is conventional inconstruetion. The mechanismincludes a revolvable, donut shaped debarking' frame 56 havingt'anannular bearing portion 57 at the forward and rear ends thereofrotatably mounted in annular races 58. Pivotally' mounted on thedebarker frame 56 intermediate for-ward andrearends of the frame andwith their nonpiv'oted ends-projecting intothe central space encompassedby frame 56 are a'series of debarking arms'or members-6 1. These armshave scraper or hoe portions 62'at their inner, nonpivoted ends whichare operable 'to' scrape against the peripheral surface of a log'to'remove its bark on rotation of frame 56 about the log. The 'sides of thedebarkiug arms facing the infeed side of the apparatus slop'e away fromtheinfeed side and have a spiral turn, enabling theen'd of a loggto pushthe arms radially outwardly when the log end is initially thrustinternecenter of the debarking framet', Suitablemechanism- (not shown)yieldably urges'the inner ends of arms 61' and hoe portions 62 radiallyinwardly against a log with a predetermihedforce. i P 9 The ringdebarker mechanism, as are the upperclamp; ing mechanisms of the infeedand o'utfeed clamping means, is mounted for movement up and down in averti cal path. The radial'center-of the annular debark-ing mechanism ismovable'upand down in-a vertical'plane extending: through thelongitudinal'center'of a log passing through the apparatus. The reducedcenter portions of the various rolls of the infeed and outfeed clampingmeans center a log longitudinally with the radial center of the ringdebarker, and the centralporti'ons of the; upper clamping mechanismsmove up and down in this same vertical plane. v I

With respect to the mounting of the ring debarke'r, races 58 supportingthe ring frame of the debarker arecarried in a carriage structureindicatedfgenerally; at'71'. This structure comprises forwardand rear"mounting plates 70 (see Fig. 2) to which races 58 are-rigidly secured asby welding Plates 70 are fastened securely t'o a sjkeletonized structureformed of vertical side members 72, transverse members 73, andlongitudinal and horizontal interbracing members 74.. The ends. of theplates on each side of the, apparatus are, interconnected by hood plates75. i V a j The. carriage is slidable up and down centrally be tween twosets of'opposed vertical members 13,,and" is centered between thesemembers against longitudinal shifting by shoes' 76secured to thecarriage, andsliding on face, portions of members13; A pair of pulleys8'1 rotatably secured to opposite ends of aninterhraceme'niber 74'located on each side of the carriage ride} up 'and' down on flange.portions of members 13" and hol'd the; carriage from shifting laterallyand out' of'alignment with the path of a log transported through theapparatus.

s e together with' the debarking arm's mounted on the frame' isrotated'in races by means,

78, 79.: Belt 79,.is reeved-directly-about ring frame .56, the ringframe being provided with a cylindrical pulley surface about its outerperiphery.

. Motor means are provided for moving the carriage and the ring debarkermechanism up and down. This comprises a pair of single actingpiston-cylinders or jacks 86, 87'(expansible-contractible motors)disposed one on one side and one on the other side of the carriage, andeach connected at one end to the carriage 71 and at its other end toframe member 12 of main frame 11.

It will be noted that a pair of piston-cylinders are employed for movingthe ring debarker mechanism up and down, and that a singlepiston-cylinder is used for each of the forward and rear clamping rolls23, 51. Piston-cylinders 23, 51 are of substantially the same size..Each may be the same size as, or somewhat smaller than,piston-cylinders 86, 87. In the usual instance,-

the piston-cylinders are powered from the same high pressure fluidsupply. As a consequence, clamping rolls 23, .51 move when adjusted atabout twice the'speed of the ringdebarker mechanism. l 1

. Control means'or mechanism is provided for regulating movement of thevarious parts and interconnecting the ring debarking mechanism and theforward clamping roll 23 whereby movement of one is accompanied bymovement of the other. The control mechanism and the parts employed arebest shown schematically in Fig. 3. While some of the control parts areshown in Figs. 1 and 2, many of the valves, fluid lines, and controlcomponents have been excluded from these figures for reasons of clarity.

"Referring to Fig. l, secured to a sliding block 37 on one side of theapparatus isa bracket 91 to which is secured a pair of cams 92 and 93.Cams 92 and 93 are spaced vertically one from the other, and each movein a vertical path up and down with upper roll 23. The cams are offsetlaterally'one from the other, so that the vertical path of cam 92 liesbeside but is laterally offset from the vertical path of cam 93. r

' Secured to an upright frame member 13 on the same side of theapparatus as cams 92, 93 is the cylinder portion of an elongatedpiston-cylinder device 96. A rod 97 for the piston-cylinder extendsthrough the entire length of the piston-cylinder, and has secured to itslower end a plate or follower member mounting a pair of cam operatedsignal valves designated S1 and S2. These are laterally offset as arethe cams. Signal valve S1 is aligned with cam 92 so that anactuatingfinger for the valve will engage cam 92 on relative movement ofthe two parts past each other, to actuate the valve. Signal valve S2 isaligned in a similar manner with cam 93.

Actuation of piston-cylinder 96 produces movement vertically either upor down of valves S1, S2, and valves S1 and S2 move in parallel pathsadjacent the parallel paths of cams 92 and 93.

Secured in fixed position to the frame member 13 mounting cylinder 96 isthe cylinder portion of another piston-cylinder device 101. The cylinderof piston-cylinder 101 is secured to the frame laterally outwardly fromthe frame so as to be out of the way of movable carriage 71. The rod ofpiston-cylinder 101 extends through the entire length of thepiston-cylinder, and has its lower end atlixed to an interbrace member74 of carriage 7 1. In this manner, movement of the ring debarkermechanism is accompanied by movement of the piston of piston-cylinder101.

The upper end of piston-cylinder 101 is connected by conduit 102 to thelower end of piston-cylinder 96. The lower end of piston-cylinder 101 isconnected by conduit 103 to the upper end of piston-cylinder 96. Theconduits constitute means forming a closed circuit between the twopiston-cylinders, and providing for fluid interchange between the twodevices. When fluid is displaced from the upper portion ofpiston-cylinder 101 by raising its piston, the fluid displaced entersthe' lower end of the. piston chamber andcauses the piston of t his.device.

to rise a proportionate amount. Lowering ofithe piston.

of device 96 takes place in a similar manner.

Since the piston rods of both piston-cylinders 96, 101 extend entirelythrough the cylinders of the devices, each device has equaldisplacements on opposite sides of the piston for the device. Thepressure area of pistoncylinder 101 is twice that of piston-cylinder102. Thus movement of the piston rod of piston-cylinder 101 isaccompanied by a corresponding movement of the piston rod ofpiston-cylinder 96, but the total movement of one is exactly twice thatof the other. The two piston-cylinders constitute an hydraulic, feedbackmechanism feeding back to the follower plate mounting valves S1, S2 amovement proportioned to the movement occurring in the ring debarkingmechanism. They also constitute a pro portioning means in the controlsystem.

With reference now m Fig. 3, the hydraulic circuit controlled by camoperated signal valves S1 S2.will be. explained. In the discussion, theexpression -valve spool controlled ports" refers to those ports oflavalve which are closed or opcnedby operationof -the ,spool of the valve.The expression. ffluid actuating ports? refers to those ports of anhydraulically actuated v'alve which lead drawings, the valves are shownas elongated rectangular blocks, and the conduits shown as connectingwith the short sides of a block are connected to the fluid actuatingports of the valve. Those conduits connecting with either of the longsides of a block are connected to valve spool controlled ports. p j

As can be seen in Fig. 3, two' of the valve spool controlled ports ofcam operated signal valves S1 and S2 are connected by conduits 111, 112,and 113, 114, respectively, to the oppositely disposed .fluid actuatingports of hydraulically actuated pilot valves P1 and P2, A valve spoolcontrolledport of each of these pilot valves is con nected, by'conduits116 and 117, respectively,'toone-o the fluid actuating ports of a pilotregulatedcontrol va'lve' C1. Control valve C1 in turn regulates'theadmission or. exhaust of pressure fluid from the lower ends of singleacting piston-cylinders 86, 87 moving the debarking mechanism. Manuallyoperated valves M1, M2 and M3 provide manual means for regulating theoperation of piston-cylinders 86, 87, piston cylinder 41, andpiston-cylinder 52,-'respectively.

Valves M1, M2 and M3 are conventional three-position valves having valvespools controlling inlet and exhaust connections between four valvespool controlled ports. Each of the valves has spring means urging thespool of the valve to a neutral position located intermediate .two otherpositions. In Fig. 3, therefore, these valves (as well as all othershaving springs centering a valve spool to a neutral position) are shownwith springs indicated diagrammatically within the rectanglerepresenting the valve. Buttons are also shown to indicate that thesevalves may be operated manually.

In all the valves M1, M2, and M3 (as well as inall other three-positionvalves discussed) the dotted lines through the valve indicate the flowof fluid through the valve when the valve is in neutral position. If noline is shown for a valve spool controlled port, that port is closedwhen the spool is in neutral position. The valve spool for each valvewhen displaced upwardly in the valve in Fig. 3 produces parallelflowconnectionsin the valve, i.e., fluid flows directly across the valvefrom a spool controlled port on one side to a spool controlled portdirectly opposite. Moving the valve spool in the opposite directionproduces reverse connections, i.e., the lines of flow from a port on oneside to a port on the other side cross each other.

Cam operated signal valves S1 and S2 are also threeposition valves, andtherefore each is shown as including springs. Valves S1 and S2, insteadof being manually operated, are actuated by movement of cam fingers/121,

gees-abs 122 indicated as connected to the spools of the valves. Thecamfingers are pivoted in a conventional manner to thecasings for-thevalves, and each has a bifurcated inner end (not indicated) whichsurrounds the valve casing and, by, means of a sliding connection,produces sliding movement of a valve spool on pivotal movement of thecam finger connected thereto. In Fig. 3, when the outer, cam end of acam finger for a signal valve is pivoted downwardly, the valve spool ofthe valve is displaced upwardly and a parallel flow through and betweenopposite spool controlled ports results. Movement in the oppositedirection reverses the connections, so that a crossed flow through thevalve is produced.

Pilot valves P 1 a'nd P2 are conventional two-position valves, and are actuated only hydraulically. Since they are two-position" valves, nosprings are indicated. Pressurefluid admitted. to an actuating chamberof a valve (as in) the ease cram otherhydraulically actuated valveshereindis'cusse'd) pushes the valve spool of the valve away from'thefluid actuating port which admitted the pressure flit-id. Since valvesP1, P2, are two-position valves, the

valve spoolremains in one position until actuated in the oppositedirection. In Fig. 3, when a spool of a pilot valve moves downwardly acrossed flow throughthe spool controlled ports results, whereas pushinga spool upwardl-y produces a parallel-flow. The pilot valves have fourspool controlled ports, however it will be noted that meet the ports, ofeach. valve is indicated as plugged. (Plugs are indicated at 168, 169.)

Control valve C1 is similar to manually operated valves M1,,M2 and M3,in that it also is a threeposition valve and spring biased to a neutralposition wherein fluid flow through the valve takes place as shown bythe dotted lines indicated for the valve. The valve diflers from valvesM1, M2, and M3,, however, in that it is hydraulicallyactua-tedandnotmanually actuated.

A high pressure pii'mp 125 driven by motor 124 pumps fluid underpressurenirough high pressure conduits 126, 127 and-128 to aspoolcontrolled port of valves S1 and S2, r spectiv ly. In their neutralposition, the spools for these valves close off the ports connected toconduits 127, 128; and conduits 111, 112, 113, and114 connect to sump,indicated' at S, through conduits 137, 138.

Pump 125 also delivers fluid under pressure through conduit 131, aconventional variable restriction valve 132, and a divider valve 138, toa spool controlled port of valve M1, ,from whence fluid flows throughconduit, 133 to valve C1, through conduit 134 to valve M2, and through"conduit 136 to valve M3. The valve spools of valves C1, M2, and M3 intheir neutral position connect conduits 133, 134, 136. Divider valve 138in line 131 is conventional, and divides the pressure fluid flowing inconduit '131 to direct part of the, fluid through. conduit 139' directlyto valve M2.

Conduits 141, 142 connect spool controlled ports of valves C1 and M1,respectively, to a conduit 143 leading to the lower ends of thepiston-cylinders 86, 87 moving the ringdebarker. Conduits 146 and 147connect spool controlled ports of valve M2 with opposite ends ofpistoncylinder 41 connected to upper forward clamping roll 23. Includedin conduit line 147 is a conventional pressure reducing valve, 151responsive to the pressure in the line between the valve andpiston-cylinder 41 and regulating the maximum pressure of pressure fluidpassing through the valve. Conduits 152, 153 connect spoolcontrolledports of valve M3 with opposite ends of pistoncylinder 52 moving theupper rear clamping mechanism up anddown. Included in conduit line 153is pressure reducing valve 156 similar to valve151. Bypassing pressurereducing valves 151 and 156 are conduit segments. cOImecting withconventional relief valves 157, 158, respectively. Valves 159, 160 areconventional check valves, each accommodating unidirectional flow offluid downwardly through the. valve only. F' A low pressure pump 161driven by motor 124 pumps t ll fluid urinepressure through low p essureeohduit illtif 163, and 164 to a valve spool controlled port of valve P1and valve P2. It will be remembered that pilotvalves P1 and P2 havevalve spool controlled ports closed by plugs 168, 169, and that eachalso has a valve spool controlled port connected with a fluid actuatingport of control valve, C1. Another valve spool controlled port of valveP1 and valveP2 is connected, by conduits 171, 172, respectively, tosump. v

Low pressure pump 161 is also connected by conduit 176 through apressure reducing valve 177 similar to valves 153;, 156, to conduit 178,through the valve spool controlled ports of an hydraulically actuatedon-ofl valve 179, to conduit-180 connecting with conduit 143.- The.

spool of valve 179 connectsthe valve spool controlled 7 ports of thevalve when low pressures are in conduitI'SQ and closes, oif the portswith high pressures in"conduit valve, 181. I

Conduit 163 connects low pressurepump 161 through a conduit191, apressure reducing valve 192 (resembling valves 151, 156) and the valvespool controlled ports of an hydraulically actuated on-oif valve 193(similar to valve 179) with conduit 146 leading to the bottom end ofpiston-cylinder 41. Conduit1 91 is also connected through reducing valve192 and a relief valve 201 to sump. Pressure reducing valve 192 isfurther connected by conduit 202 and through the spool controlled portsof an hydraulically actuated on-off. valve 203 (similar to. valves 193,179), conduit 294 to conduit 152 connected to the bottom end ofpiston-cylinder 52 moving the upper rear clamping mechanism up and down.Conduit 163'leading from the low pressure pumpalso connects by conduit206 and through the valve spool controlled ports of an electricallyoperated on-ofl valve. 297 through conduit 208 to conduit 153 and theupper" side of piston-cylinder 52. Asimilar connection is pre. videdbetween conduit 163 to piston-cylinder 41 through conduit .191, thevalve spool controlled. ports of anelectrically operated on-ofif valve211, and conduit 1 47.

The electrically operated on-vofl valves 207, 211 are conventional, eachhaving valve spool controlled ports connected to each other when thesolenoid for the valve is energized, and out of communication with eachotherwhen the solenoid for the valve is deenergized. Switches 216, 217operate the valves, these switches closing a circuit between 'pairs ofsupply conductors. j

Relief valves 218, 219 connect conduits 126, 162, respectively, to sump.These are includedv as a safetyprecaution.

In general terms, high pressure pump and the conduit system connectingthis pump to the piston-cylinders moving the ring debarker mechanism andthe front and rear upper clamping rolls constitute a high pressureconduit system supplying pressure fluid to the various pistoncylindcrs.Pump 161 and the conduits associated'therewith supply pressure fluidatrelatvely low pressure for actuating pilot valves P1 and P2 controllingthe admission of pressure fluid to the actuating chambers of valve C1.Further, the low pressure pump, through reducing valve 177, conduit 178,and valve 179 provides a low pressure conduit system for introducing aconstant supply of rela tively low pressure fluid to the lower ends ofpiston cylinders 86, 87, for the purpose of partially balancing theweight of the ring debarker.

Pump 161, conduit 191, electrically operated valves 207 and211, andreducing valves 151, 156 are part of a conduit system included for thepurpose of admitting low pressure fluid. constantly to the upper side ofthe piston-cylinders moving the front and rear upperclamping rolls,whereby they may be continuously and yieldably urged downwardly with aconstant bias. This part of the circuit therefore comprises acompensator control; mechanism automatically adjusting the. positionot-the 130. Conduit 17s is connected to sump through relief:

from and rear up er clamping mechanisms whereby these clampingmechanisms follow the contour of a log while exerting a predeterminedpressure downwardly thereon. f The operation of the hereinabove setforth control system will now be described. For purposes of explanation,it will be assumed that the upper clamping mechanism of the forwardclamping means is spaced from the lower clamping mechanism apredetermined distance, and that the ring debarker mechanism is alignedwith its radial center midway vertically between the upper and lowerclamping mechanisms of the forward clamping means. In this condition,cams 92 and 93 are directly above and below cam fingers 121, 122,respectively, of the cam operated signal valves. Cam 92 is in the pathof cam finger 121 and cam 93 is in the path of cam finger 122. The twocams each constitute a first trigger means movable in a path conjointlywith the forward upper clamping mechanism, and cam fingers 121, 122 eachcomprise second trigger means engageable with a first trigger means andmovablein a path adjacent the path of a first trigger means but at aspeed determined by the speed of the ring-type debarker.

:It a log is inserted between the clamping mechanisms of the frontclampingmeans which has a diameter less than the spacing between theclamping mechanisms, an operator adjusts manual control valve M2 so thatthe spool of the valve moves downwardly in Fig. 3 producing crossedconnections between opposite spool controlled ports of the valve. Asa-result, pressure fluid from pump 125 is delivered through conduit 126,131 and valves M1 and C1 (which are in their neutral positionsltoconduit 134, through valve M2 to conduit147, Where it passes throughpressure reducing valve 151 to the'top side of piston-cylinder 41.Exhaust from the bottom side of the piston-cylinder takes place throughconduit 146, valve M2, conduit 136, valve M3, .to sump. Theupperclamping mechanism moves downwardly and with it cam 92 (cam 93movingaway from cam finger 122). Downward movementof cam 92 pivots camfinger 121 downwardly, with its inner end moving upwardly and the valvespool of signal valve S1 moving Upwardly.

Upward movement of the spool of valve S1 produces parallel connectionsbetween opposite spool controlled ports of the valve, and conduit 127connected to pump 12S delivers pressure fluid to conduit 112 and thelower actuating chamber of valve P1. The upper actuating chamber ofvalve P1 exhausts through valve S1, and conduit 138 to sump. The spoolof valve P1 moves up under the momentary admissionof pressure fluidthereto. Cam 92 on passing cam finger 121 moves over the cam finger withthe finger returning to its original position and the spool of valve S1returning to a neutral position. Movement of the valve spool of valve P1upwardly produces parallel connections through the valve, with pump 161and conduit 164 being connected to conduit 116 and the; upper actuatingchamber of valve C1.

The actuating chamber on theopposite side of valve C1 is connectedthroughconduit 117 to pilot valve P2 which is initially set so that itsvalve spool occupies a down position in the valve with crossedconnections existing between the oppositely disposed spool. controlledports of the valve. As a consequence, the lower actuating chamber ofvalve C1 may exhaust through conduit 117, pilot valve P2, and conduit172 when the spool of C1 moves down. Movement of the spool of valve C1downwardly produces crossed connections between opposite spoolcontrolled ports of the valve.

As a result, the bottom ends of piston-cylinders 86, 87 exhaust throughconduit 143, 141, and valve C1 to conduit 134 and sump. The pistons ofthe single acting piston-cylinders 86, 87 lower themselves drawing influid from sump to their opposite sides. The ringdebarker mechanismmoves downwardly together with these pistons. a p

As the annular debarker moves downwardly, fluid is wai t pumped frompiston-cylinder 101 to piston-cylinder. 96, with the follower and thecam operated signal valves moving downwardly at twice the speed of theannular debarker.

When the operator has adjusted the upper clamping mechanism of the frontclamping means to its proper position and released manual valve M2, theupper clamping mechanism becomes stationary. The ring debarker continuesits movement downwardly until cam finger 121 overtakes cam 92 and movesacross it. This movement produces upwardly movement of the cam fingerrelative to signal valve S1, and downward movement of the spool in thevalve. As a consequence, pump 125 pumps fluid through signal valve S1 toconduit 1'11 and the upper fluid actuating chamber of pilot valve P1.The lower fluid actuating chamber of the valve exhausts through valve S1to conduit 138 and sump. Downward movement of the spool of pilot valveP1 takes place. Theupper fluid actuating chamber of valve C1 exhauststhrough conduit 116 and pilot valve P1, and the spool of valve C1returns to a neutral position. In this position, exhaust for con duits143, 141 is shut off, and the ring debarker stops.

Since the follower mounting valves S1, S2 moves at twice the speed ofthe ring debarker, total movement of the debarker before it is stoppedalways equals half that of the forward upper clamping mechanism.Piston-cylinders 96, 101 thus constitute step down means in the device.Operation of the mechanism is similar when the upper clamping mechanismof the forward clamping means is moved upwardly instead of downwardly.In this instance, when the clamping mechanism is moved upwardly, cam 92moves away from cam finger 121 and cam 93.moves across cam finger 122 topivot it upwardly with downward movement of the valve spool in signalvalve S2. This produces a crossed connection between the oppositelydisposed spool controlled ports of valve S2, and pressure fluid isadmitted to conduit 114 and the bottom of valve P2, exhaust from the topof valve P2 occurring through conduit 113. Pilot valve P2 (whichpreviously had its valve spool disposed downwardly therein) is moved upwardly, and pressure fluid from conduit 164 passes through theparallelly connected spool controlled ports of valve P2 to conduit 1-17and the lower actuating chamber of valve C1. The upper actuating chamberof valve C1 exhausts through valve P1 (its valve spool resting in a downposition).

Pressurizing of the lower actuating chamber of valve C1 moves the valvespool upwardly in Fig. 3, and pressure fluid flows from pump through thevalve to conduits 141, 143 and the lower ends of piston-cylinders 86,87. This raises the ring debarker.

When the adjusted position of the forward upper clamping mechanism isreached, the follower mounting the cam operated single valve S1 and S2overtakes the cams, movement of cam finger 122 over cam 93 occurs, thecam finger pivots downwardly, and the valve spool of signal valve S2moves upwardly. Pressure fluid is admitted to conduit 113, and the spoolof valve P2 moves downwardly. Valve C1 assumes a neutral position andmovement of the ring debarker ceases.

To obtain automatic following of the forward or rear upper clampingrolls of the device, electrically operated valves 211 and 207 are used.Considering the front upper clamping mechanism, if switch 216 is closed.and the solenoid of valve 211 energized, the valve is opened with theintroduction of pressure fluid from pump 1-61..through conduit 191 toconduit 147, reducing valve .1'51and the upper end of thepiston-cylinder 41. As a result, a constant pressure is exerteddownwardly on the upper front clamping mechanism determined bythe'setting of the pressure reducing valve. If the diameter of a logmomentarily increases as it passes through the front clamping means, byreason of a knot or other irregularity, the upperfront clamping rollrriechanism moves upwardly whey 11 the upward pressure on the mechanismexceeds the downward pressure produced in piston-cylinder 41 by theintroduction of pressure fluid to its upper end. Reducing valve 192admits a relatively small amount of pressure fluid through valve 193 andconduit 146 to the lower side of piston-cylinder 41. This prevents avacuum condition from being set up in the lower part of thepiston-cylinder on upward movement of the clamping mechanism. Onthe'other hand, if the log diameter decreases, the piston ofpiston-cylinder 41 moves downwardly under the urging of pressure fluiddelivered to the top of the piston-cylinder through pressure reducingvalve 151. Exhaust from the lower part of piston-cylinder 41 takes placethrough valve 193 and reliefvalve 201 (which is set to open at apressure only slightly above the pressure of fluid flowing throughreducing valve 192).

. Hydraulically operated on-off valve 193 is included to enable raisingof the front hold-down roll. When pump 125 is connected to conduits 134,147, the high pressure resulting in line 147 operates to close valve193. Pressure fluid is delivered directly to piston-cylinder 41 to raiseits piston without bleeding of the pressure fluid through valve 193 andrelief valve 201 to sump.

The hydraulic compensator circuit for the rear upper clamping mechanism(roll 46) is substantially the same as the circuit just described. Valve207 corresponds to valve 211, and when actuated by closing of switch217,

permits the introduction of fluid from pump 161 through reducing valve156 to the upper end ofpiston-cylinder 52. Downward movement of itspiston is enabled by the discharge of fluid from the bottom end of thepiston-cylinder through conduits 152, 2114, 'valve 203, conduit 202 andrelief valve 2121. When valve M3 is actuated to raise roll 46, valve 203is closed by the pressure existing in line 204, to prevent bleeding ofpressure fluid through conduit 202 and valve 201.

When switch 216 is closed and valve 211 opened, it will be apparent thatby incorporation of the feedback and follower system disclosed, movementof, the upper front clamping mechanism either up or down as a logprogresses through the apparatus is accompanied by automaticcompensating movement in the ring debarker. This is a highly desirablefeature.

Concerning the hydraulic balancing means included in the control systemwhich partially balances the mass of the-ring debarker mechanism,conduit 162 connects pump 161 through a reducing valve 177 to conduits178, 143 and the lower ends of piston-cylinders 86, 87. Thus aregulated, relatively low pressure is delivered at all times to thebottom ends of these piston-cylinders tending to raise their pistonportions against the weight of the ring debarker. Pressure reducingvalve 177 is adjusted so that the-pressure is not sufiicient to actuallyproduce rising movement of the ring debarker. Hydraulically actuatedon-off valve 179 performs the same function in this part of thecircuitas on-oft valves 193 and 203. If the annular debarker is to be raised,the relatively high pressure of fluid introduced into conduit 143functions to close valve 179 to prevent bleeding of pressure fluidthrough valve 181.

Fig. 4 illustrates an electric circuit such as may be used incontrolling the admission of pressure fluid to pistoncylinders 86, 87.In this figure, a solenoid operated valve C2 is included to perform thefunction of hydraulically operated valve C1 shown in Fig. 3. Solenoidoperated valve C2 is a three-position valve (spring biased to a neutralposition) having opposed spool controlled ports 221, 222, and 223, 224.Ports 222, 224 are connected to conduits 134, 133 of the systemdisclosed in Fig. 3, port 221 to conduit 1-40, and port 223 to conduit141. The electrical components shown in Fig. 4 generally replace camoperated signal valves S1, S2, the pilot valves P1 and P2,. and thevarious conduits interconnecting these ports;

l2 switches SW1 and SW2. These correspond to'cam opera ated valves 51and S2. Cam operated fingers 2.31 and 232 control switches SW1 and SW2.As in the case of the first embodiment, cam 92 moves up and down in thepath of one finger (finger 231), and cam 93 moves up and down in thepath of another finger (finger 232).

Switches SW1 and SW2 are conventional, each having four switch points,indicated at 240 through 244, and 246 through 249. Associated with pairsof switch points in each switch is a switch contact, exemplified bycontact 250. These are each spring biased, in the case of the upper pairof switch points of a given switch to a closed position, and in the caseof the lower pair of switch points of a given switch to an openposition. The cam finger of Referring to Fig. 4, moun-ted on thefollower and movtable with the annular debarking mechanism are a pair ofeach of the switches is pivoted to the switch body, and has a forked endor rocker portion 251 abutting the switch contacts of the switch. Theends of each rocker portion are free of the switch contacts they abut.Thus, in action, if the rocker portion of a switch is pivoted in aclockwise direction in Fig. 4, the connections between the upper pair ofpoints in the switch is opened, and the lower'pair of switch pointsremain disconnected. If the rocker portion is pivoted in the otherdirection, the upper pair of switch points remain connected, whereas aconnection is produced between the lower pair of switch points.

Switch SW1 controls a solenoid 261 ganged to the valve spool of controlvalve C2, and when energized is operable to move it downwardly. SwitchSW2 controls solenoid 262 ganged to the valve spool of valve C2 and isoperable when energized to move it upwardly. Solenoid 263 is the holdingsolenoid for the circuit controlling solenoid 261, this solenoid beingganged to a pair of switches 266, 2 67. Solenoid 271 is the holdingsolenoid for the circuit controlling solenoid 262, this solenoid beingganged to switches 272 and 273. 5 V

In operation, when the forward upper clamping mechanism of the forwardclamping means is moved downwardly to move cam 92 down across finger231, a closed contact exists momentarily between switch contacts 243,244 and solenoids 263, 261 are energized. This closes switches 266, 267,switch 267 acting as a holding switch keeping solenoid 263 energized,and switch 266 maintaining solenoid 261 energized. As a result, thevalve spool of valve C2 moves downwardly, a crossed connection isproduced between the fluid controlled ports of the valve, and pressurefluid flows from conduit 133 to conduit and sump. The cross connectionalso connects conduit 141'to conduit 134, and exhaust from the bottomends of piston-cylinders 86, 87 takes place, with the ring debarkermoving downwardly.

. As in the case of the first embodiment, when the moveinent of theforward clamping roll is stopped, cam finger 231 overtakes cam 92 and ispivoted in the opposite direction. This serves momentarily to open theconnection be tween points 241, 242. Solenoid 263 is deenergized and asa consequence, solenoid 261 becomes deenergized with the valve spool ofvalve C2 returning to a neutral position.

Movement of the upper clamping mechanism of the forward clamping meansupwardly, in a similar manner, causes ene'rgizing'of solenoids 271 and262. The valve spool of C2 is moved upwardly, parallel connections areproduced, and pressure fluid flows from conduit 133. to conduit 141.When movement of the clamping mechanism stops, and the cam finger 232overtakes cam 93, the. cam finger is pivoted in the opposite directiontode energize solenoids 271, 262, and to cause the spool of controlvalveC2 to return to a neutral position.

It is claimed and desired to secure by Letters Patent:

1. In ring-type debarking apparatus having a pair of opposed clampingmechanisms adapted to engage opposite sides of a log passed endwise in apath therebetween, annular debarking mechanism rotatable about a logadvanced between said clamping mechanism, and mounting meansmountingoneof saidclampingmechanisms and said debarking mechanismaccommodating movement of the two mechanisms in directions which occupya commonplaneextendinglongitudinally of a log advanced between saidclamping mechanisms, the improvement comprising a first motor meansconnected to and moving said one clamping mechanism, a second motormeans connected to the debarking mechanism for moving the' debarkingmechanism, and control means regulating said second motor meansresponsive to the position of said one clamping mechanism, said controlmeans having a pilotmeans, means operatively connecting the pilot meansto said one'clarnping mechanism whereby it is regulated by the positionof said one clamping mechanism and means operatively connecting saidpilot means to said second motor means whereby the pilot meansregulates" the second motor means and thus controls the position of saiddebarking mechanism.

Q2, Self-adjusting ring-type debarking apparatus comprising a frame,apair of opposed clamping mechanisms and means mounting the clampingmechanisms on said frame, one over the other, the means mounting theupper of said clamping mechanisms accommodating movement thereofvertically toward and away from the lower of said clamping mechanisms,annular debarking mechanism rotatable about ,a ,log advanced endwisebetween said clamping mechanisms and mounting means mounting thedebarking mechanism on said frame rearwardly of said clampingmechanisms, ,said last-mentioned mounting meansaccommodating movementofthe debarkingmechanism ina vertical direction, manually controlledfluid motor means connected to said upper clamping mechani-smforadjusting its position to enable moving of the same-against a logdisposed between the clamping mechanisms, compensator meansautomatically adjusting the position of saidiupper clamping mechanism tocompensate for variations, in the diameter of a log and holding saidupper clamping mechanism against. a log with a predetermihedpressurqasecond motor means connected to said, debarking mechanism for moving thedebarking mechanism, and control means regulating said second motormeans responsive to the position oi said upper clamping mechanism.

3 The apparatus of claim 2 wherein said control means comprises pilotmeans operatively connected to said second motor means to activate thesame, and means for actuating said pilot means, said means for actuatingsaid pilot means being operatively connected to the upper clampingmechanism and the debarking mechanism so as to be responsive to theposition of both of the two mecha- 'nisms and including proportioningmeans whereby the pilot means is actuated, to initiate activation ofsaid second motor means by movement of said upper clamping mechanismtoward an adjusted position, and actuated to deactivate said secondmotor means by movement of said upper clamping mechanism into anadjusted position and movement of said debarking mechanism a distanceequal to a predetermined fraction of the total movement -occurring'insaid upper clamping mechanism.

4. In ring-type debarking apparatus having a pair of .opposed clampingmechanisms adapted to engage opposite sides of a log passed endwise in apath therebe- -t'ween','a'nnula'r debarking mechanism rotatable about a'log' advanced between said clamping mechanisms, and mounting meansmounting one of said clamping mechanisms and said debarking mechanismaccommodating movement'of the two mechanisms in directions which-occtipYakommonplane extending longitudinally of a log fadvan'cedbetween saidclamping' mechanisms, the improvement comprising a firstmotor means connected to andrpr moving" said one clamping mechanism, asecond motor means connected to and for moving said debarking:m'echanism, "and control means regulating said second motor meansresponsive to the position of said one clampingmechanism,said controlmeans having a first trigger means movable in a path and meansoperatively connect- -ing said-first trigger means and saidone clampingmecha- :14 nism whereby the triggerrneans moves conjointly with saidone'clamping mechanism, a second trigger means engageable with "saidfirsttrigger means and] movable in a path adjacent the path of saidfirst trigger means and means operatively connecting said second triggermeans and said debarking mechanism whereby the second trigger mechanismmoves conjointly with said debarking mechanism, the means connectingsaid second trigger means and debarking mechanism having proportioningmeans whereby the second trigger means moves at a speed that is apredetermined multiple of the speed of said debarking mechanism, thepilot means connected to said second motor means actuated to initiateactivation of said second motor means by engagement of said first andsecond trigger means on initial movement of said one clamping mechanismtoward an adjusted position, said] pilot means being actuated by asubsequent engagement of said trigger means to deactivate said secondmotor means.

5. The debarking apparatus of claim Mix/herein the means connecting thesecond trigger means and debarking mechanism comprises a followermounting said second trigger means, and hydraulic mechanism operativelyconnected between saiddebarking mechanism and follower, said hydraulicmechanism having a pair of expansible piston-cylinder devices,eachhaving equal displacements on opposite sides of the piston for thedevice, and conduit t means interconnecting said piston-cylinder devicesforming a closed hydraulic circuit thereinbetween, one of saidpiston-cylinders being connected to said debarking mechanism, the otherof said piston-cylinders being connected tosaid follower. i

6. In ring-type debarking apparatus having a pair of opposed clampingmechanisms adapted to engage opposite sidesof a log passed endwise in apath thereinbetween, one clamping mechanism being movable toward andaway from the other, and annular debarking mechanism mounted rearwardlyof said clamping mechanismsrotatabie about a log advanced between saidclamping mechanisms, said debarking mechanism being movable in adirection substantially parallel to the direction of movement of saidone clamping mechanism, the improvement comprising servo motor meansconnected to said debarking apparatus for moving the same, and controlmeans regulating said servo motor means responsive to the position ofsaid one clamping mechanism, said control means having pilot means foractivating and deactivating said servo motor means, a first triggermeans movable in a path conjointly with movement of said one clampingmechanism, a follower and means connecting said follower to saiddebarking mechanism for movement conjointly with said debarkingmechanism but at a speed which is a predetermined multiple of the speedof said debarking mechanism, and a second trigger means mounted on saidfollower engageable with said first trigger means and movable in a pathadjacent said first trigger means, said first and second trigger meansengaging each other and actuating said pilot means to activate saidservo motor means on initial movement of said one clamping mechanism toan adjustedposition, said first and second trigger means engaging eachother and actuating said pilot means to deactivate said servo motormeans upon movement of said clamping mechanism into an adjusted.position.

7. In a ring-type debarking apparatus having a frame, a pair of opposedclamping mechanisms mounted on said frame adapted to engage oppositesides of a log passed endwise in a path thereinbetween, and annulardebarking mechanism mounted on said frame rearwardly of said clampingmechanisms rotatable about a log advanced between said clampingmechanisms, one of said clamping mechanisms and said debarking mechanismbeing movable mechanisms and mounted for movement in directions whichoccupy a common plane extending longitudinally through the center of alog advanced between said clamping mechan sms. the. improvementycomprising motor means for moving s id debarking mechanism, and control meansfor said motor means, said control means comprising a follower, a pairof expansible piston-cylinder devices having piston and rod ends, eachhaving equal displacements .on opposite sides of the piston for thedevice, one of said piston-cylinder devices having a total displacementvolume equal to a fraction of the total displacement volume of. theother, closed conduit means connecting the cylinders of said devices forfluid inter change, means securing one of said ends of one of saiddevices to said frame and the other of said ends of said one device toone of said movable mechanisms, means securing one of said'ends of theother vof said devices to said frame and the other ofsaid ends of saidother device to said follower, and triggering means interposed betweensaid follower and the other of said movable mechanisms connected to saidmotor, means foractivating and deactivating s'aid motor means. I

l sgln' aring-typefdebarking apparatus having a pair of opposed clampinginechanisms adapted to engage opposite sides of'a log passed endwise ina path thereinbetween, and annular debarking r'nechanism,mountedearwardly of said clamp'ingmechanhrnsrotatable about a log advancedbet'weensaid clampingmechanisms, one of said clamping mechanisms andsaid deba'rking mechanism being movable mechanisms and mounted formovement in directions which occupy a common plane extending'longitudinally through the center of a log advanced between saidclamping mcchanisms, the improvement comprising a first motor means formoving 'said one clamping mechanism, a servo motor means for moving saiddebarking' mechanism, "and control means for said servo motor means,said control means comprising a first trigger means movable in a pathconjointly with one of said movable mechanisms, a follower and a secondtrigger means mounted on said follower; feedback means moving saidfollower conjointly with the other of said mechanisms in a path adjacentthe path of sad first triggermeans, said first and second trigger" meansbeing engageable with each other, said feedback means moving saidfollower at a speed different from but related to the speed of movementof said other mechanism, and pilot means actuated by engagement of saidfirst and second trigger means for activating said second motor means.

9. In a ring-type debarking apparatus having a pair of opposed clampingmechanisms adapted to engage opposite sides of a log passed endwise in apath thereinbetwcen, and annular deb-arking mechanism mounted rcarwardlyof said clamping mechan sms rotatable about a log advanced between saidclamping mechanisms, one of's aid clamping mechanisms and said debarkingmechanism being movable mechanisms and mounted for movement indirections which-occupy a common plane extending longitudinally throughthe center of a log advanced between said clamping mechanisms, theimprovement comprising 'a first fluid, motor means operable to move,when activated, said one clamping mechanism at a predetermined rate ofspeed, a second fluid motor means operable to move, when actuated, saiddebarkng mechani'sm'at a predetermined rate of speed which is not morethan half the rate of speed of movement of said one clamping mechanism,and control means for said second fluid motor means, saidcontrol meanscomprising a firsttrigger means movable in a path conjointly with saidone. clampingmechanism, a follower and a second trigger means mounted onsaid follower, feedback means moving said follower .conjointly with saiddebarking mechanism in a path adjacent the path of said first triggermeans, said first and second trigger means being engageable with eachother, said feedback means moving sa d follower at a rate of speed whichis greater than but not more than twice the speed of movement of said sln mechanism; afldpilot means actuated. by

t l c '16 e sem t 0f s ifir'st n eco idit l sse means for,activating'said second fluid motor means. 10. In a ringype deb'arkingapparatus having a frame, a pair of pposed clamping mechanismmountedfion said frame adapted to engage opposite sides of a log passedendwise thereinbetween, and annular debarking mechanism mounted on saidframe rearwardly of said clamping mechanisms rotatable about a logadvanced be tween said clamping mechanisms, one of said clampingmechanisms, and said deb'a'rking' mechanism being mounted for movementin directions occupying a com-1 mon plane extending longitudinallythrough the center of a log advanced between said clamping mechanisms,the improvement comprising a first fluid motor ime'an's o'per able tomove, when actuated, said one clamping mecha nism at a predeterminedrate of speed anda manually operated control therefor, a second fluidmotormcans operable I01 move, when actuated' Said debarking mecha nismat a predetermined rate of speed which is 'not more tha half the rateof'sp'eed of said first fluid motor means, and control means regulatingsaid second fluid motor means, said control means comprising a movablefollower, a pair of 'expansiblepiston-cylinder devices hav ing pistonand rod ends, each having equal displace ments on opposite sides of thepiston for the device, one' of said devices having a total displacementvolume equal to approximately twice that of the other, closed conduitmeans connectingth'e cylinders of said devices for fluid interchange,means connecting one of said ends'of said one device to said frame andthe other of said ends; of the device to said debarking mechanism, meansconnecting" one of said ends'of the other device to said frame and' theother of said ends'of the device to said follower, a pair of cooperatingtrigger means, one mounted on said follower and one mounted on said oneclamping mechanism, respectively, said triggermeans moving in parallelpaths past positions whil'ethey engage with one another, and pilot meansactuated by mutual engagement of said trigger means to activate saidsecond fluid motor means. 11. In ring-type debarking apparatus havinginfeed clamping means for advancing a log along a path through theapparatus and an annular debarking mechanisfn'on the outfeed side ofsaid clamping means rotatable about a'log advanced in said path, thecombination of expansible-contractible fluid motor means connected to,said debarking mechanism for raising and lowering the same, highpressure conduit means supplying pressure fluid at relatively'highpressure tosaid fluid motor means and to the side thereof' wherein thefluid motor means is actuated to' raise the debarking mechanism andcontrol means therefor regulating the flow of pressure fluid respondingto variations in the diameter of a log passing through the apparatus,and a second conduit means introducing pressure fluid constantly atrelatively low pressure to the same side of said fluid motor means.

12. In ring-type debarking apparatus having infeed clamping means foradvancing a log along a path through the apparatus and an annulardebarkingmechanisrn on the outfeed side of said clamp ng means rotatableabout a log advanced in said path, the combination ofexpansible-contractible fluid motor means connected to said debarkingmechanism movable in one direction to lift and in the other drection tolower the same, a first conduit means introducing aconstant supply of.pressure fluid to one side of said fluid motor means and urging thelatter in a lifting direction withla forcenot exceeding that required toraise the debarkingmechanism, a second conduit means introducingpressure fluid to said one sideof said fluid motor means under apressure sufliclent to raise the debarking -mechanism,,and control meansresponding to variations. in the d ameter of a log passing thr ugh theap aratus regulating the flow of pressure fluid through said secondconduitrneans.

113; It; ringetypedebarking apparatus thecombination' of a frame, a pairof opposed clamping mechanisms and means mounting the clampingmechanisms on said frame, one over the other, the means mounting theupper of said clamping mechanisms accommodating movement thereofvertically toward and away from the lower of said clamping mechanisms,annular debarking mechanism rotatable about a log advanced endwisebetween said clamping mechanisms and mounting means mounting thedebarking mechanism on said frame rearwardly of said clampingmechanisms, said last-mentioned mounting means accommodating movement ofthe debarking mechanism in a vertical direction, expansible-contractiblefluid motor means connected to said debarking mechanism for raising andlowering the same, high pressure conduit means supplying pressure fluidat relatively high pressure to said flu d motor means and to the sidethereof wherein the fluid motor means is actuated to raise the debarkingmechanism and control means therefor regulating the flow of pressurefluid through the conduit means, low pressure conduit means introducingpressure fluid constantly at relatively low pressure to the same side ofsaid fluid motor means, and power-actuated means for moving said upperclamping mechanism to adjusted positions, the control means for saidhigh pressure conduit means being actuated by movement of said upperclamping mechanism responding to the spacing of said pair of opposedclamping mechanisms.

14. In ring-type debarking apparatus the combination of a frame, a pairof opposed clamping mechanisms and means mounting the clampingmechanisms on said frame, one over the other, the means mounting theupper of said clamping mechanisms accommodat ng movement thereofvertically toward and away from the lower of said clamping mechanisms,annular debarking mechanism rotatable about a log advanced endwisebetween said clamping mechanisms and mounting means mounting thedebarking mechanism on said frame rearwardly of said clampingmechanisms, exnansible-contractible fluid motor means connected to saiddebarking mechanism for raising and lowering the same, a first conduitmeans introducing a constant supply of pressure fluid to one side ofsaid fluid motor means and urging the latter in a lifting direction witha force not exceeding that required to raise the debarking mechanism, asecond conduit means introducing pressure fluid to the same side of saidfluid motor means under a pressure suificient to raise the debarkingmechanism, control means for said second conduit means regulating theflow orf fluid through, and power-actuated means for moving said upperclamping mechanism to adjusted positions, the control means for saidsecond conduit means being actuated by movement of said upper clampingmechanism.

15. The combination of claim 14 wherein said poweractuated means formoving said upper clamping mechanism comprises a secondexpansible-contractible fluid motor means connected thereto and movablein one direction to lift and in the other direction to lower theclamping mechanism, said last-mentioned fluid motor means having highpressure, manually controlled conduit means for the supply of pressurefluid to both sides of the motor at relatively high pressure, and lowpressure conduit means introducing a constant supply of pressure fluidat relatively low pressure to the side of said fluid motor means whereinsaid clamping mechanism is urged in a lowering direction.

16. In a ring-type debarking apparatus having a pair of opposed clampingmechanisms adapted to engage opposite sides of the log passed endwise ina path thereinbetween, and annular debarking mechanism mountedrearwardly of said clamping mechanisms rotatable about a log advancedbetween said clamping mechanisms, one of said clamping mechanisms andsaid debarking mechanism being movable mechanisms and mounted formovement in directions which occupy a common plane extendinglongitudinally through the center of a log advanced between saidclamping mechanisms, the improvement comprising a first motor means formoving said one clamping mechanism, a second motor means for moving saiddebarking mechanism, and control means interconnecting the actuation ofthe first and second motor means whereby one is a servo motor means andis actuated in response to actuation of the other, said control meansincluding proportioning mechanism whereby the total movement produced insaid one clamping mechanism by actuation of said first motor means is :apredetermined multiple of the total movement occurring in said debarkingmechanism on actuation of said second motor means.

17. In a ring-type debarking apparatus having a pair of opposed clampingmechanisms adapted to engage opposite sides of a log passed endwise in apath thereinbetween, annular debarking mechanism rotatable about a logadvanced between said clamping mechanisms, and mounting means mountingat least one of said clamping mechanisms and said debarking mechanismaccommodating movement of the two mechanisms in directions which occupya common plane extending longitudinally of a log advanced between saidclamping mechanisms, said one clamping mechanism and said debarkingmechanism constituting adjustable mechanisms, the improvement comprisinga first motor means connected to and for moving said one clampingmechanism, a second motor means connected to and moving said debarkingmechanism, and control means regulating one of the motor meansresponsive to actuation of the other of the motor means, said controlmeans having a first trigger means movable in a path and meansoperatively connecting said first trigger means and said one clampingmechanism whereby the trigger means moves conjointly with said oneclamping mechanism, a second trigger means engageable with said firsttrigger means and movable in a path adjacent the path of said firsttrigger means and means operatively connecting said second trigger meansand said debarking mechanism whereby the second trigger means movesconjointly with said debarking mechanism, the means connecting one ofsaid trigger means to its respective adjustable mechanism includingproportioning means whereby the movement occurring in said one triggermeans on movement of the last-mentioned adjustable mechanism is amultiple of the movement occurring in the adjustable mechanism, andpilot means operatively connected to one of said motor means forcontrolling the same, said first and second trigger means regulatingsaid pilot means.

References Cited in the file of this patent UNITED STATES PATENTS2,591,751 Whitlock Apr. 8, 1952 2,765,012 Riddell et a1. Oct. 2, 1956FOREIGN PATENTS 39,704 Sweden Dec. 1, 1915

